1. Field of the Invention
The present invention relates.to an apparatus for filtering a solvent included in air inside a main body of a liquid electrophotographic printer.
2. Description of the Related Art
In a liquid electrophotographic printer, for example, a color printer, ink which is a mixture of liquid norpar (C.sub.12 H.sub.26) that is a solvent and toner in a solid phase is used for printing. That is, when the ink is supplied to a photoreceptor belt where an electrostatic latent image is formed, the toner adheres to the photoreceptor belt according to the electrostatic latent image to form a predetermined image. Here, a small amount of the solvent remaining on the photoreceptor belt together with the toner is vaporized by a drying unit and is collected by a solvent collection system.
FIG. 1 shows a solvent collection system of a liquid electrophotographic printer. Referring to the drawing, a drying unit includes a drying roller 22 contacting a photoreceptor belt 14 and absorbing a liquid solvent therefrom, a heating roller 23 for vaporizing the absorbed solvent by heating the drying roller 22, and a manifold 21 housing the drying roller 22 and the heating roller 23.
The solvent adhering the photoreceptor belt 14 is absorbed by the drying roller 22 and vaporized by the heating roller 23. The vaporized solvent is temporarily contained inside the manifold 21. Since fins 21a for heat exchange are formed at the outer surface of the manifold 21, part of the vaporized solvent is condensed on the inner surface of the manifold 21 due to heat exchange with outside air and then is collected into a cartridge 26 via a first collection pipe 25.
The remaining solvent in a gas phase flows to a condensation receptacle 28 along a supply line 27 by the operation of a supply fan 29. The gaseous solvent flowing into the condensation receptacle 28 is liquefied by heat exchange with liquid solvent 28a contained in the condensation receptacle 28. When the level of the solvent in the condensation receptacle 28 rises due to condensation of the gaseous solvent, part of the solvent is collected into the cartridge 26 via a second collection pipe 31.
Also, the gaseous solvent that is not condensed in the condensation receptacle 28 flows into a filtering apparatus via a line L2 by the operation of an exhaust fan 33 and is filtered by a filter 34 of the filtering apparatus.
An exhaust line L1 is a route for exhausting air to prevent an excessive increase in the temperature of a printing unit 11 in a main body 10 during printing. The air exhausted along the line L1 is also filtered by the filter 34 so that solvent possibly remaining inside the main body 10 can be filtered.
Reference numeral 30 indicates a Peltier chip for maintaining the temperature inside the condensation receptacle 28. Reference numeral 32 indicates a moisture separation unit for separating moisture from the liquefied solvent 28a stored in the condensation receptacle 28 and storing the separated moisture.
Conventionally, a carbon filter such as activated charcoal is used as the filter 34. However, since the carbon filter easily loses its filtering capacity by repeated filterings, it is inconvenient to frequently exchange the carbon filters. Further, disposal of filtered solvent together with the filter causes pollution problems.